Ringed accretion disks: instabilities

TL;DR

This paper investigates the formation of multiple instability points in ringed accretion disks around Kerr black holes, analyzing how the black hole's spin influences the number of possible instabilities.

Contribution

It introduces a model of multi-torus accretion disks and analyzes the limits on instability points based on black hole spin and disk configuration.

Findings

Number of instability points is limited by black hole spin.

Instability points depend on the relative rotation of the tori.

The model accounts for both corotating and counterrotating rings.

Abstract

We analyze the possibility that several instability points may be formed, due to the Paczy\'nski mechanism of violation of mechanical equilibrium, in the orbiting matter around a supermassive Kerr black hole. We consider recently proposed model of ringed accretion disk, made up by several tori (rings) which can be corotating or counterrotating relative to the Kerr attractor due to the history of the accretion process. Each torus is governed by the general relativistic hydrodynamic Boyer condition of equilibrium configurations of rotating perfect fluids. We prove that the number of the instability points is generally limited and depends on the dimensionless spin of the rotating attractor.